Boris Johnson has accused General Qassem Soleimani of being “a threat to all our interests” and said “we will not lament his death” as he called for de-escalation from all sides.
After speaking to US President Donald Trump on Sunday, the Prime Minister issued his first statement on the spiralling crisis in the Middle East after the US’s fatal drone strike on Iran’s top military leader.
Mr Johnson warned that all calls for reprisals “will simply lead to more violence in the region and they are in no one’s interest” in the wake of the killing in Baghdad on Friday.
But a short while later, Mr Trump threatened to “strike back” and “perhaps in a disproportionate manner” if Iran strikes a US citizen or target.
Meanwhile, Iran announced it will abandon the limits in the unravelling nuclear deal on fuel enrichment, its uranium stockpile and research activities in a move that could bring it closer to assembling an atomic bomb.
The PM said he will be speaking to Iraq “to support peace and stability” after its parliament called for the expulsion of foreign troops, including British soldiers working against so-called Islamic State.
“General Qassem Soleimani posed a threat to all our interests and was responsible for a pattern of disruptive, destabilising behaviour in the region,” Mr Johnson added.
“Given the leading role he has played in actions that have led to the deaths of thousands of innocent civilians and western personnel, we will not lament his death.
“It is clear however that all calls for retaliation or reprisals will simply lead to more violence in the region and they are in no one’s interest.”
Mr Johnson, who was facing criticism for his silence while on holiday in the Caribbean during the escalating crisis, also said he had spoken to French President Emmanuel Macron and German Chancellor Angela Merkel.
Downing Street said the PM arrived back in the UK on Sunday, but did not say whether he was in Number 10.
Ministers are due to meet on Monday to discuss the crisis that has raised fears of all-out war and the Foreign Office will update Parliament on Tuesday.
A non-legally binding bill passed by Iraq’s parliament called for the expulsion of all foreign forces.
Some 400 UK troops are stationed in Iraq in the fight against IS, while the US has 5,200, prompting fears of a withdrawal that could cripple the battle against the terror group.
The Ministry of Defence was understood to be awaiting the decision of the Iraqi government before acting over the soldiers based there as part of the US-led coalition.
A UK Government spokesman said: “The coalition is in Iraq to help protect Iraqis and others from the threat from Daesh (Islamic State), at the request of the Iraqi government.
“We urge the Iraqi government to ensure the coalition is able to continue our vital work countering this shared threat.”
In response to the killing of Gen Soleimani on Friday, Iraqi prime minister Adel Abdul-Mahdi said the parliament could end the presence of foreign troops or restrict their mission training local forces. He backed the first option.
Foreign Secretary Dominic Raab had spoken to him on Sunday morning in the wake of the killing of the head of the elite Quds Force, who masterminded Tehran’s security strategy in the region.
Mr Raab was defending the Mr Trump’s decision to launch the drone strike, accusing hardliners in Tehran of “nefarious behaviour” and saying the US has the “right of self defence”.
But his call for the pursuit of a diplomatic route to bring Tehran “in from the international cold” came as Iran accused the US president of breaching international law.
“The US will take their own operational judgment call but they’ve got the right of self defence,” Mr Raab told Sky’s Sophy Ridge on Sunday.
“So we understand the position the US were in and I don’t think we should be naive about the Iranian Revolutionary Guard or indeed General Soleimani.”
The Foreign Secretary also defended Mr Johnson, saying he has been in “constant contact” with the PM who remained “in charge” throughout his holiday.
As Mr Raab was speaking, Iran’s foreign minister Mohammad Javad Zarif struck back at the president’s Twitter threat to target 52 Iranian sites “very fast and very hard” if Tehran attacks US assets.
Mr Zarif accused Mr Trump of having “committed grave breaches” of international law with the killing and of threatening to commit a “war crime” by targeting cultural sites.
Labour’s shadow foreign secretary Emily Thornberry warned of a “lurch towards war” arising from the president’s “reckless” decision to kill the general.
The Foreign Office strengthened travel advice to Britons across the Middle East including Saudi Arabia and Turkey, while the Navy was to begin accompanying UK-flagged ships through the key oil route of the Strait of Hormuz.
Related: General Qassem Soleimani: A targeted killing? Or an assassination?